This invention relates to an instrument for the placement of a stent in a body canal and particularly to an instrument including means for the correct positioning of a self-expanding stent in a body canal, and means for releasing the stent in a retrograde manner.
Tubular prostheses for transluminal implantation in body canals, for example blood vessels, for the purpose of repair or dilation are known in the art. These prostheses, referred to herein as stents, may be tubular elements which are non-extendible or extendible (i.e. adapted to extend longitudinally), or they may be self-expanding in the transverse direction.
A typical self-expanding stent is disclosed in U.S. Pat. No. 4,655,771, which stent has a radially and axially flexible, elastic tubular body with a predetermined diameter that is variable under axial movement of ends of the body relative to each other and which is composed of a plurality of individually rigid but flexible and elastic thread elements defining a radially self-expanding helix. The disclosure in U.S. Pat. No. 4,655,771 is incorporated herein by reference.
Placement of the stent according to U.S. Pat. No. 4,655,771 in a body vessel is achieved in one embodiment by a device which comprises the use of a piston or, in another embodiment, by use of latch means to push the stent forward.
U.S. Pat. No. 4,768,507 discloses a stent insertion apparatus which includes an inner core member with a spiral groove formed on its outer surface, which groove cooperates with an outer sheathing to form a spiral cavity adapted to contain an expandable coil stent.
U.S. Pat. No. 4,732,152 discloses a device for the implantation of a radially expandable prosthesis comprising hose means for maintaining the prosthesis in a radially contracted state around a concentric flexible probe and means for releasing the prosthesis from said probe.
U.S. patent application Ser. No. 569,267 (now U.S. Pat. No. 5,026,377) describes and claims in combination, a self-expanding braided stent (such as that disclosed in U.S. Pat. No. 4,655,771) and an instrument for the deployment or retraction in a body canal of said stent, which comprises an elongated tubular outer sleeve having a proximal end and a distal end, an elongated core disposed within said sleeve and movable relative to said sleeve, said core being longer than said sleeve and having a proximal end and a distal end and including a grip member at or near said distal end of the core, said grip member being an integral portion of the core or a sleeve or coating attached around the periphery of the core and being adapted to: (i) releasably hold said self-expanding stent within said outer sleeve, (ii) deploy said stent beyond the distal end of said outer sleeve when said outer sleeve is moved in a backward direction relative to said core and (iii) retract said stent back within said outer sleeve when said core is pulled in a backward direction relative to said outer sleeve.
It has now been found that location means for the correct positioning and fixing of the instrument before release of the stent may be incorporated in the instrument. Also means for releasing the stent in a retrograde manner may be incorporated in the instrument. Additionally both said location means and said retrograde releasing means may be combined in a single instrument.